Pavement



Sept. 2 1924. 1,5()7282 w. C. HAMMATT PAVEMENT Filed April 14. 192s A 1'TORNE Y Patented Sept. '2, 1924.

UNITED STATES y 1,501,282 PATENT OFFICE.'

WILLIAM CSHING HAMMATT, 0F SAN' FRANCISCO, ALIFOBNIA.

PAVEMENT.

Application nica prix 14, 192s. serial No. 631,999.

To all whom it may concern;

Be it known that I, WILLIAM CUsHiNG HAMMAM', a citizen of theUnited`States, residing at 1125 Francisco .,Street, in the city andcounty of San Francisco, State of California, have invented a new anduseful Improvement in P`avements,.of which the following is a full,clear, and exact description, reference being had to the accompanyingdrawin forming a partof this specification an explaining its nature.-

' My invention relates to ari improvement.) p

in the class of pavements which are wholly or partially composed ofPortland cement concrete.

The pavements composed wholly and in part of concrete formed of amineral aggregate, bound together by Portland cement. as usually andheretofore designed and constructed, are faulty in the followingparticular, to wit:

Said Portland cement concrete is placed in a thin slab directly incontact with the subsoil, and during the process of setting of theconcrete the original water from they mixture is drawn therefrom by thecapillary action ofsaid subsoil, weakening said slab at the bottom andfor a certain .distance toward the interior-of the slab. The proportionof ,the slab affected by the removal or de lotion of its water contentvaries with the thickness ofthe slab, and 'in slabs of the; ordinarythickness of from four to six inches, the weakening is very materialregardless of what manner of curing the up er surface of the slab may beemployed. y improvement consists in the interposing between the subsoiland the slab sufficient water proofing material to eliminate thecapillary action of the subsoil, thus reproducing in effect the resultsattained in. laboratory -tests in slab construction. v Y

I attain this object in the manner illustrated on the accompanyingdrawing, in which- Figure 1 is a vertical section of a pavementconsisting of a slab of Portland cement concrete and water procngcomposed of overlapping layers of building paper, roofing felt or otherfabric of a like nature, laid on a prepared subgrade;

Figure 2 is a vertical section through the pavement composed of two ormore courses, the lowest of which is composed of Portland cementconcrete, and a water proofing layer consisting of building paper,roofing felt or other water proof fabric laid on a prepared subgrade;

Figure 3 'is a vertical section through a pavement consisting of,Portland cement con'- crete laid on a prepared subgrade water proofedby means of asphalta tar, oil or other similar material applied directlyto said subrade by means of spraying, pouring, rushing, swabbing orraking without the use of a fabric; and Figure 4 is a vertical sectionthrough a avement consisting of two or more courses, the lowest of whichis composed of Portland cement concrete laid on a repared subgrade waterproofed with aspha t, tar, oil or other similar material applied bysprinkling, pouring, painting, brushing or raking on said subgrade-without the use of a fabric.

lIn Figure 1 the'l letter (a) re resents the water proofing layer,letter (bi) the subsoil, the letter (c) represents the cement concretepavement. In Figure@ the letter (a) represents the water proofing layer,letter (b) represents the subsoil, letter (c) represents the cementconcrete base, and letter. (d) represets the wearing surface. In Figure3' the wetter (a) represents the water proofing layer, letter (b)represents the subsoil, letter l(c) represents the cement concretepavement, and in Figure 4 theletter (a) represents the water proofinglayer, letter (b) represents the subsoil, letter. (c) represents thecement concrete base and the letter (d) represents the wearin surface.In the figures shown on the attac d drawing, and hereinabove described,it is not the intention to make them or any part of them of aparticular-scale, or to limit the improverepresentsl of the variousparts of which the pavement is com osed.

In t e following claim the word pavenient is intended to mean and ishereby defined as any slab resting on the soil', either in its naturalstate or artificially prepared by excavating or lling, for the purposeet v distributing superimposed weight or taking abrasive wear, whethersaid slab is used in the construction of vehicular roadways, sideawalks, athletic elds, building oors, 'tank bottoms, or whatsoeversimilar structure.

composed of mineral aggregate, Portland 6 cement and water in anyproportion, separatedfrom the subsoilby a water proof sheet consistingof building paper, roofing felt or any kind of fabric water proof incharacterl before laying or made so in the process of laying by means ofasphalt, tar,

oil, paint or other water repellent element or com ound..

'W LIAM CUSHING HAMMATT. Witnesses:

' WESTON SMALL,- J T ULLocK.

